In the Noah's Ark story, the dove returned with an olive leaf to show that the waters had receded. Genesis 8:11 says Noah recognized from the freshly plucked olive leaf that the floodwaters had diminished from the earth. The detail became one of the narrative's best-known symbols of returning life and peace.
Noah sent the dove out again seven days later, and it did not return. That absence indicated that the bird had found a place to land. The story therefore uses the bird's behavior as a practical test of whether the surrounding land was becoming habitable.
The text specifically says “olive leaf,” not a generic leaf or branch. Later art often depicts a dove carrying a larger branch, which is an artistic expansion of the biblical detail. The olive branch's broader peace symbolism developed through later religious and cultural traditions.